Hydrometallurgical process for selective dissolution of mixtures of oxy compounds

ABSTRACT

The invention provides a process for the selective dissolution of oxygenated compounds containing at least one non-ferrous metal selected from the group consisting of nickel, zinc, and copper, present in a mixture of oxygenated compounds containing said at least one non-ferrous metal and at least one element selected from the group consisting of lead, cobalt, iron, manganese, and silicon, and comprises suspending the mixture of the oxygenated metallic compounds in an aqueous phase which, preferably, contains chloride and alkaline earth metal ions; treating the resulting aqueous suspension, maintained at a pH exceeding about 1, with chlorine, preferably at a temperature ranging from about 60° C. to the boiling point of the suspension, to selectively solubilize the said at least one non-ferrous metal while the said at least one element remains in an essentially insoluble residue; and separating the aqueous solution containing the dissolved said at least one non-ferrous metal from the insoluble residue. The starting mixture of the oxygenated compounds is exemplified by the product resulting from the roasting of a nickel matte, a basic carbonate of nickel, a mineral oxide of zinc, and the dust of a blast furnace.

This is a continuation of application Ser. No. 950,446, filed Oct. 11,1978, which is a continuation of 904,306, filed May 9, 1978, nowabandoned, which is also a continuation of 765,813, filed Feb. 4, 1977,now abandoned.

The present invention relates to a hydrometallurgical process for theselective dissolution of mixtures of metallic oxy compounds; it relatesparticularly to the selective putting into solution of certainnon-ferrous metals present in these mixtures.

In the course of the putting into operation of processes by which puremetal is obtained from mineral, the metallurgist often meets mixtures ofmetallic oxy compounds. These mixtures can be met at any stage of theextraction of the metal, from the mineral, which can be a mixed oxide,up to the residues from the refining of the metals. One may cite asexamples of such mixtures, the products of roasting of pyrites, theproducts of roasting of nickel mattes and the basic carbonates of nickel(B.N.C.) which are derived from a first reduction of the mineralfollowing ammoniacal lixiviation.

In order to continue the process of extraction of the metal or metals,it is necessary to separate one from the other and, in particular toseparate iron which is very often present in minerals of non-ferrousmetals and which is then found in variable proportions in the firststages of the purification of these metals.

To carry out this separation, one proceeds, in general, to put intosolution the metals to be recovered; this dissolution is most often doneby means of hydrochloric or sulphuric acid; however, these dissolutionsare not selective and appreciable amounts of iron are found in the finalsolutions.

This is why it is an aim of the invention to provide a process for theselective dissolution of oxides of non-ferrous metals which permitstheir separation from iron, manganese and silica. PG,5

More particularly, an aim of the invention is to provide a process ofselective dissolution of nickel oxide which allows it to be separatedfrom oxides of cobalt, lead and copper.

Another aim of the invention is to provide a process of selectivedissolution of zinc oxide which allows it to be separated from oxides ofcopper and lead.

Another aim of the invention is to provide a process of selectivedissolution of copper oxide which allows it to be separated from leadoxide.

According to the invention, these aims and others which will becomeapparent later are obtained by means of a process described below.

This process consists essentially in putting into suspension in anaqueous phase the mixture of oxides to be treated and then subjectingthis suspension to the action of chlorine.

The term "oxygenated compounds" as used herein is intended to include alarge number of compounds including oxides, hydroxides, carbonates,basic carbonates, and even certain sulphates and silicates.

The chlorine necessary for the operation of this process is introducedin any convenient manner; it can thus be synthesised in situ by chemicalor electrochemical means or introduced into the solution in the form ofgaseous chlorine.

Although it is possible to carry out the process at elevatedtemperatures, it is more convenient to perform the dissolution at atemperature below that of the boiling point of water and preferablybetween 60° and 100° C.

The selectivity of the dissolution depends greatly on the pH and it isimportant to keep the pH beyond certain values which vary according tothe oxide which it is desired to preferentially dissolve; in general,the pH should not be below the value of 1-2 and more often 3-4; this whyit can be necessary to provide systems to keep a minimum pH. This isparticularly important whilst the mixture contains much sulphur in itselemental form or as sulphide; the oxidation of sulphur by chlorineindeed causes a significant liberation of acidity.

It is also possible to vary the selectivity of the dissolution byvarying the composition, the complexing agents such as the chloride ionand the pH of the aqueous phase which serves to suspend the mixture ofoxygenated compounds.

Thus, strong concentrations of chloride ion bring about an easiersolution of the metals which form the complexes with the chloride ion.

It may also be noted that the presence of calcium ions strongly lowersthe concentration of sulphate ions and thus allows an easier dissolutionof metals which have insoluble sulphates and particularly of lead; bycontrast, the presence of sulphate ions prevents the dissolution ofplumbous ions.

This process of dissolution is particularly noteworthy by reason of itsselectivity. At first, only the zinc and the nickel are dissolved, thenas the process is continued copper is dissolved, and then lead whichonly dissolves in aqueous phases which are rich both in chloride ionsand in ions of alkaline earth metals (calcium, strontium, barium,radium). Neither iron, manganese, cobalt nor silica are dissolvedappreciably.

It will be appreciated that such a selective dissolution process isadvantageous; indeed, not only does it allow separation of nickel andcobalt, or of zinc, copper and lead, but it also allows the purificationof iron, cobalt and manganese which remain insoluble in theseconditions.

The invention will be further described with reference to a preferredembodiment indicated in the accompanying drawing, but this descriptionis not limitative of the invention.

The single FIGURE of the drawing is a diagramatic flowsheet of theprocess according to the invention.

Referring to this FIGURE, the mixture of oxygenated compounds to betreated arrives at 1 in an apparatus A where it is suspended in asolution which is introduced at 2. The suspension which leaves at 3 fromA enters a reactor B where it is subjected to the action of gaseouschlorine which is introduced at 5.

The solution obtained after the reaction is removed from B at 6 andintroduced at 7 into a decanting vessel D where the larger particles areseparated from the solution and removed in the form of a suspension at9. The thus clarified solution is led into a filtration apparatus Cwhere the solid and liquid phases are then separated; the solid phase isremoved at 11 whilst the liquid phase is drawn off at 12 and is passedto another type of apparatus (not shown) where it is subjected tofurther treatments to produce metal salts or pure metals.

The solid phase which leaves at 11 from C is led at 13 into an apparatusA' in which it is subjected to suspension in an aqueous phase whichenters at 14; this aqueous phase can be water, or a solution derivedfrom another stage of the dissolution process if it is desired tooperate an apparatus consisting of more than 2 stages. The suspensionleaves at 15 from A' and enters at 16 a reactor B' in which it is mixedwith the suspension which leaves at 9 from D and which enters at 18 intoB'; the mixture of the two suspensions is then subjected to a bubblingof chlorine which is introduced into the vessel B' at 17.

The solution which leaves at 19 from B' is led at 20 into a filtrationapparatus C' where the solid and liquid phases are separated; the liquidphase is recovered at 22 and returned at 2 into A, whilst the solidphase is removed at 21; the solid phase can be discarded, or subjectedto a further dissolution in the case of a multistage installation.

The stage of decantation can sometimes be omitted, in which case thesolution which leaves at 6 from B is directly passed into the vessel Cat 10.

The following non-limitative examples are provided to further illustratethe invention and to enable the experts to determine the suitableoperating conditions in each particular case.

In the tables below, the abbreviation "n.d." means "not determined".

METHOD OF OPERATION OF EXAMPLES I TO VII

In a reactor equipped with a cooling coil, an agitator, a thermometerand a pipe for injection of chlorine, there was poured the desiredamount of water or of a solution of sodium chloride or calcium chloride,and then the mixture of oxygenated compounds was added either in onebatch or little by little.

The resultant suspension, kept under constant agitation, was thenbrought to the working temperature. Injection of chlorine into thereactor was then commenced and continued during the duration of thereaction. At regular intervals, samples were taken in order that thecourse of the reaction should be followed.

At the end of the reaction, the reaction mixture was filtered and themother liquor recovered; the residual cake was then washed with waterand the washing water covered. The mother liquor, the washing water andthe residual cake were analysed. The cake could then be subjected to anew dissolution in chlorine. Then, the co-efficient of selectivity K wascalculated according to the formula: ##EQU1## e.g., if Nickel is theregarded metal and if Iron is the impurity: ##EQU2##

EXAMPLE 1

    ______________________________________                                        Mixture to be treated                                                                            1 kg of wet B.N.C. con-                                                       taining 16.89% by weight                                                      of nickel                                                  Aqueous phase for the                                                                            500 ml water                                               suspension                                                                    Amount of chlorine injected                                                                      40 g per hour                                              Duration of the reaction                                                                         7 hours                                                    Working temperature                                                                              75° C.                                              ______________________________________                                    

(a) Change in pH and amount of nickel in solution as a function of time

    ______________________________________                                        Duration of the                                                                         Amount of Ni.sup.++  in                                                                      pH of reaction mixture                               reaction (hours)                                                                        the solutions obtained                                                                       at 75° C.                                     ______________________________________                                        0         0.040          7.5                                                  1/2       6.2            6.1                                                  1         15.8           5.8                                                  2         36.0           5.4                                                  3         54.4           4.8                                                  4         73.0           4.3                                                  5         84.2           4.0                                                  6         87.0           3.7                                                  ______________________________________                                    

(b) Results of the dissolution.

The results of the analysis of the cake, the mother-liquors and thewashing waters are given in the following table together with thecomposition of the starting mixture:

    __________________________________________________________________________               COMPOSITION                                                                   of the           of the                                                       initial                                                                            of the                                                                              of the                                                                              cake                                                                              K with                                                   product                                                                            mother-                                                                             washing                                                                             (fully                                                                            respect to                                               (dry)                                                                              liquor                                                                              waters                                                                              dry)                                                                              iron (mother-                                            (%)  (g/l) (g/l) (%) liquor)                                       __________________________________________________________________________    Nickel (Ni)                                                                              47.00                                                                              97    52    50  590                                           Cobalt (Co)                                                                              0.65 3.4.10.sup.-3                                                                       0.6.10.sup.-3                                                                       4.40                                                                              1.3                                           Iron (Fe)  0.20 0.7.10.sup.-3                                                                       ≦0.2.10.sup.-3                                                               0.95                                              Manganese (Mn)                                                                           0.05 0.5.10.sup.-3                                                                       ≦0.1.10.sup.-3                                                               0.31                                                                              2.9                                           Zinc (Zn)  0.08 0.18   32.10.sup.-3                                                                       nd  640                                           Copper (Cu)                                                                              0.07 0.018  2.3.10.sup.-3                                                                      nd  72                                            Lead (Pb)  ≦0.001                                                                      nd    nd    nd                                                Sulphate (SO.sub.4.sup.--)                                                               4.95 17.8  4.3   2.60                                              Total Sulphur (S)                                                                        2.41 5.9   1.5   0.96                                              Carbon dioxide (CO.sub.2)                                                                6.99 nd    nd    nd                                                Ammonia (NH.sub.3)                                                                       0.51 ≦20.10.sup.-3                                                                ≦20.10.sup.-3                                                                nd                                                Chromium (Cr)                                                                            ≦0.002                                                                      nd    nd    nd                                                Aluminium (Al)                                                                           ≦0.005                                                                      nd    nd    nd                                                Bismuth (Bi)                                                                             ≦0.005                                                                      nd    nd    nd                                                Tin (Sn)   ≦0.005                                                                      nd    nd    nd                                                Sodium (Na)                                                                              <0.01                                                                              nd    nd    nd                                                Calcium (Ca)                                                                             nd   nd    nd    nd                                                __________________________________________________________________________    Final pH                     3.7                                              Volume of mother-liquor recovered                                                                          760 ml                                           Volume of washing water recovered                                                                          1240 ml                                          Dry weight of residual cake  50 g                                             Yield of the dissolution of the nickel                                                                     85%                                              __________________________________________________________________________

EXAMPLE II

    ______________________________________                                        Mixture to be treated                                                                            1000 g of B.N.C.                                                              containing 16.89% of                                                          nickel                                                     Aqueous phase for the                                                                            500 ml of 1 M sodium                                       suspension         chloride                                                   Amount of chlorine 40 g per hour                                              injected                                                                      Duration of the reaction                                                                         5 hours                                                    Working temperature                                                                              75° C.                                              ______________________________________                                    

The results of the analysis of the cake, the mother-liquor and thewashing water are given in the following table together with thecomposition of the (fully dry) starting mixture:

    __________________________________________________________________________               COMPOSITION                                                                   of the                                                                        dried                                                                              of the                                                                             of the     K with                                                   initial                                                                            mother-                                                                            washing                                                                             of the                                                                             respect to                                               product                                                                            liquors                                                                            waters                                                                              cake iron (mother-                                            (%)  (g/l)                                                                              (g/l) (%)  liquors)                                      __________________________________________________________________________    Nickel (Ni)                                                                              47.00                                                                              105  36.5  51   110                                           Cobalt (Co)                                                                              0.65 0.13 0.004 3.90  1                                            Iron (Fe)  0.70 0.004                                                                              0.002 0.71 --                                            Manganese (Mn)                                                                           0.05 ≦0.0001                                                                     ≦0.0001                                                                      0.23 <1                                            Zinc (Zn)  0.08 0.150                                                                              0.049 0.034                                                                              108                                           Copper (Cu)                                                                              0.07 0.025                                                                              0.0046                                                                              0.23  18                                           Lead (Pb)  ≦0.001                                                                      0.001                                                                              ≦0.0001                                                                      0.0005                                                                             50≦                                    Sulphate (SO.sub.4.sup.--)                                                               4.95 20.0       1.95                                               Total sulphur (S)                                                                        2.41 6.6        1.30                                               Carbon dioxide (CO.sub.2)                                                                6.99 nd                                                            Ammonia (NH.sub.3)                                                                       0.51 nd                                                            Chromium (Cr)                                                                            ≦0.002                                                                      nd                                                            Aluminium (Al)                                                                           ≦0.005                                                                      nd                                                            Bismuth (Bi)                                                                             ≦0.005                                                                      nd                                                            Tin (Sn)   ≦0.005                                                                      nd                                                            Sodium (Na)                                                                              <0.01                                                                              15                                                            __________________________________________________________________________    Volume of mother-liquor      850 ml                                           Volume of washing water recovered                                                                          1200 ml                                          Dry weight of residual cake  68 g                                             Yield of the dissolution of the nickel                                                                     79.3%                                            __________________________________________________________________________

EXAMPLE III

    ______________________________________                                        Mixture to be treated                                                                            1000 g of B.N.C.                                                              containing 16.89%                                                             nickel                                                     Aqueous phase for the                                                                            500 ml of 1.3 M calcium                                    suspension         chloride solution                                          Amount of chlorine injected                                                                      1.3 M                                                      Duration of the reaction                                                                         6 hours                                                    Working temperature                                                                              75° C.                                              ______________________________________                                    

The results of the analysis of the cake, the mother-liquor and thewashing water are given in the following table, together with thecomposition of the starting mixture:

    __________________________________________________________________________               COMPOSITION                                                                   of the                                                                        dried                                                                              of the                                                                             of the     K with                                                   initial                                                                            mother-                                                                            washing                                                                             of the                                                                             respect to                                               product                                                                            liquors                                                                            waters                                                                              cake iron (mother-                                            (%)  (g/l)                                                                              (g/l) (%)  liquor)                                       __________________________________________________________________________    Nickel (Ni)                                                                              47.00                                                                              91   48    38.8 390                                           Cobalt (Co)                                                                              0.65 0.01 0.005 2.9   3                                            Iron (Fe)  0.70 0.001                                                                              0.0007                                                                              0.47                                               Manganese (Mn)                                                                           0.05 0.002                                                                              0.0008                                                                              1.56  8                                            Zinc (Zn)  0.08 0.120                                                                              0.066 0.018                                                                              300                                           Copper (Cu)                                                                              0.07 0.044                                                                              0.015 0.15 125                                           Lead (Pb)  ≦0.0001                                                                     0.026                                                                              0.008 0.0005                                                                             ≦5000                                  Sulphate (SO.sub.4.sup.--)                                                               4.95 1.9  2.2   18.23                                              Total sulphur (S)                                                                        2.41 nd                                                            Carbon dioxide (CO.sub.2)                                                                6.99 nd                                                            Ammonia (NH.sub.3)                                                                       0.51 nd                                                            Chromium (Cr)                                                                            ≦0.002                                                                      nd                                                            Aluminium (Al)                                                                           ≦0.005                                                                      nd                                                            Bismuth (Bi)                                                                             ≦0.005                                                                      nd                                                            Tin (Sn)   ≦0.01                                                                       nd                                                            Calcium (Ca)    13.8                                                          __________________________________________________________________________    Volume of mother-liquors recovered                                                                         820 ml                                           Volume of washing waters recovered                                                                         1060 ml                                          Dry weight of residual cake  94.5 g                                           Yield of the dissolution of the nickel                                                                     77.2%                                            __________________________________________________________________________

EXAMPLE IV

    ______________________________________                                        Mixture to be treated                                                                          300 g of residue containing                                                   80% water derived from a first                                                attack on B.N.C.                                             Aqueous phase for the                                                                          300 ml water                                                 suspension                                                                    Amount of chlorine injected                                                                    40 g per liter                                               Duration of the reaction                                                                       5 hours                                                      Working temperature                                                                            75° C.                                                ______________________________________                                    

The results of the analysis of the cake, the mother-liquors and thewashing waters are given in the following table together with thecomposition of the starting mixture:

    ______________________________________                                                  COMPOSITION                                                                     of the                                                                        dried    of the    of the                                                     initial  mother-   washing                                                                              of the                                              product  liquors   waters cake                                                (%)      (g/l)     (g/l)  (%)                                     ______________________________________                                        Nickel (Ni) 45       65.80     22.10  45.5                                    Cobalt (Co) 2.63     0.003     0.03   9.95                                    Iron (Fe)   0.67     0.0001    0.0002 1.90                                    Manganese (Mn)                                                                            0.24     0.004     0.0002 0.63                                    Zinc (Zn)   0.040    0.110     0.037  0.025                                   Copper (Cu) 0.27     0.170     0.046  0.31                                    Lead (Pb)   nd       ≦0.0003                                                                          0.0003 ≦0.010                           Sulphate (SO.sub.4.sup.--)                                                                nd       5.50      1.80   1.14                                    Total sulphur (S)                                                                         nd       1.80      0.62   0.40                                    ______________________________________                                        Volume of mother-liquors recovered                                                                      450 ml                                              Volume of washing waters recovered                                                                      430 ml                                              Dry weight of residual cake                                                                             22 g                                                Yield of the dissolution of the nickel                                                                  68.5%                                               Final pH                  3.3                                                 ______________________________________                                    

EXAMPLE V

    ______________________________________                                        Mixture to be treated                                                                              134 g of a residue of                                                         B.N.C. after two                                                              successive attacks                                       Aqueous phase for the                                                                              180 ml water                                             suspension                                                                    Amount of chlorine injected                                                                        40 g per hour                                            Duration of the reaction                                                                           5 hours                                                  Working temperature  75° C.                                            ______________________________________                                    

The results of the analysis of the cake, the mother-liquors and thewashing waters are given in the following table together with thecomposition of the starting mixture:

    ______________________________________                                                  COMPOSITION                                                                     of the                                                                        dried    of the    of the                                                     initial  mother-   washing                                                                              of the                                              product  liquors   waters cake                                                (%)      (g/l)     (g/l)  (%)                                     ______________________________________                                        Nickel (Ni) 51       2.5       8.3    43                                      Cobalt (Co) 6.3      0.27      0.0007 11.30                                   Iron (Fe)   1.1      0.0009    0.0005 2.30                                    Manganese (Mn)                                                                            0.40     0.0002    0.0002 0.70                                    Zinc (Zn)   0.06     0.065     0.022  0.04                                    Copper (Cu) 0.38     0.20      0.059  0.34                                    Lead (Pb)   nd       0.0002    0.0002 0.18                                    Sulphate (SO.sub.4.sup.--)                                                                nd       1.20      0.58   1.13                                    Total sulphur (S)                                                                         nd       0.46      0.20   nd                                      ______________________________________                                        Volume of mother-liquor recovered                                                                       175 ml                                              Volume of washing water recovered                                                                       220 ml                                              Dry weight of residual cake                                                                             10.5 g                                              Yield of the dissolution of the nickel                                                                  57%                                                 Final pH                  2.2                                                 ______________________________________                                    

EXAMPLE VI

    ______________________________________                                        Mixture to be treated                                                                            125 g of an oxide derived                                                     from moderate roasting of                                                     a matte at about                                                              700°-800° C.                                 Aqueous phase for the                                                                            1 liter of water                                           suspension                                                                    Duration of the introduction                                                                     6 hours                                                    of the oxide                                                                  Amount of chlorine injected                                                                      37 g per hour                                              Duration of the addition of                                                                      6 hours                                                    chlorine                                                                      Working temperature                                                                              95° C.                                              ______________________________________                                    

The reaction was allowed to continue for one hour after the end of theaddition of chlorine.

The results of the analysis of the cake, the mother-liquors and thewashing waters are given in the following table together with thecomposition of the starting mixture:

    ______________________________________                                                  COMPOSITION                                                                     of the dried                                                                             of the mother-liquors                                              initial product                                                                          and the washing waters                                             %          %                                                      ______________________________________                                        Nickel (Ni) 72.23      42                                                     Cobalt (Co) 1.75       0.002                                                  Iron (Fe)   3.25       0.002                                                  Sulphate (SO.sub.4.sup.--)                                                                nd         9.7                                                    Total sulphur (S)                                                                         2.70       nd                                                     ______________________________________                                        Volume of mother-liquors recovered                                                                         110 ml                                           Volume of washing waters recovered                                            Yield of the dissolution of the nickel                                                                     45.5%                                            Final pH                     5.0 (95° C.)                              ______________________________________                                    

EXAMPLE VII

    ______________________________________                                        Mixture to be treated                                                                            125 g of an oxide derived                                                     from moderate roasting of                                                     a matte at about                                                              700°-800° C.                                 Aqueous phase for the                                                                            1 liter of water                                           suspension                                                                    Duration of the introduction                                                                     5 hours (6.25 g each                                       of the oxide       quarter hour)                                              Amount of chlorine injected                                                                      19 g per hour                                              Duration of the addition of                                                                      12 hours                                                   chlorine                                                                      ______________________________________                                    

The reaction was allowed to continue for 7 hours after the end of theaddition of chlorine.

The results of the analysis of the cake, the mother-liquors and thewashing waters are given in the following table together with thecomposition of the starting mixture:

    ______________________________________                                                 COMPOSITION                                                                   of the                                                                        dried  of the     of                                                          initial                                                                              mother-liquor                                                                            the    K with                                               product                                                                              & the wash-                                                                              cake   respect to                                             %        %          %    iron cobalt                               ______________________________________                                        Nickel (Ni)                                                                              72.23    53.6       46   1227 658                                  Cobalt (Co)                                                                              1.75     ≦0.002                                                                            4.7                                            Iron (Fe)  3.25     ≦0.002                                                                            9                                              Sulphate (SO.sub.4.sup.--)                                                               nd       10.8       nd                                             Total sulphur (S)                                                                        2.70     nd                                                        ______________________________________                                        Volume of mother-liquor recovered                                             and                           1110 ml                                         Volume of washing water recovered                                             Dry weight of residual cake   36 g                                            Yield of the dissolution of the nickel                                                                      78%                                             Final pH                      3.4                                             ______________________________________                                    

EXAMPLE VIII

Trial of continuous dissolution of an oxide of nickel

A trial for a continuous period of five days was carried out on amicropilot scale according to the scheme represented in FIG. 1. As thedrawing shows, the lixiviation of the oxide was carried out in twocascade reactors of about 2 liters, the first being fed with the initialoxide previously suspended in the filtrate obtained from the outlet ofthe second reactor which, itself, is fed by a suspension in water of theresidue leaving the second reactor.

The temperatures and durations of lixiviation were identical in eachreactor and respectively equal to 95° C. and 12 hours. The rate of feedof oxide was 25 g per hour and that of the incoming water was 170 ml perhour. The charge of chlorine was equal to twice the stoichiometricquantity with respect to nickel, namely 41 g per hour.

After continuous operation of about 100 hours, there were obtained asolution of nickel chloride and a residue.

The results of the analysis of the residue and of the lixiviationsolution are shown in the following table together with the compositionof the starting mixture:

    ______________________________________                                                 COMPOSITION                                                                   of the dried                                                                          of the            K with                                              initial lixiviation       respect to                                            product   solution  of the     co-                                            %         g/l       residue                                                                             iron balt                                ______________________________________                                        Nickel (Ni)                                                                              68.8      84        22    1830 220                                 Cobalt (Co)                                                                              1.8       0.010     5.3                                            Iron (Fe)  3.0       ≦0.003                                                                           10.3                                           Total Sulphur (S)                                                                        2.30      2.9       0.17                                           ______________________________________                                        Yield of the dissolution of nickel                                                                      84%                                                 pH of the lixiviation solution                                                                          4.3                                                 ______________________________________                                    

EXAMPLE IX

Treatment of a zinc oxide mineral obtained from the slag heaps of apaper factory in France

The mineral treated was composed essentially of clay (SiO₂ +Al₂ O₃+MgO), of carbonates (CaCO₃ -MgCO₃), of iron oxide (limonite), of leadoxide and of smithsonite (ZnCO₃).

    ______________________________________                                        Mixture to be treated 129.4 g                                                 Aqueous phase for the suspension                                                                    1000 ml of water                                        Charge of chlorine    20 g per hour                                           Duration of the reaction                                                                            6 hours                                                 Working temperature   85° C.                                           ______________________________________                                        KINETICS OF THE ATTACK                                                        Composition                                                                   of the fully                                                                  dry starting   Composition of the solution after                              product        (g/l)                                                          Element (%)        1 h    2 h  3 h  4 h  5 h  6 h                             ______________________________________                                        Zinc (Zn)                                                                             8.2        6.70   7.04 7.56 7.64 7.68 7.72                            Lead (Pb)                                                                             4.5        0      0    0    0    0.1  0.1                             Magnesium                                                                             2.5        2.18   3.02 3.16 3.16 3.16 3.16                            (Mg)                                                                          Calcium 5.1        3.76   4.88 4.95 5.15 5.20 5.20                            (Ca)                                                                          Iron (Fe)                                                                             6.25                                                                  pH                 3.5    2.9  2.35 2.32 1.9  2.1                             Chloride                                                                              nd         20.15  33.02                                                                              32.84                                                                              34.79                                                                              34.26                                                                              32.84                           (Cl.sup.-)                                                                    ______________________________________                                    

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                      Yield of                                            Composition                                                                          COMPOSITION        the attack                                          of the fully                                                                         of the                                                                             of the                                                                             of the   with res-                                           dry starting                                                                         starting                                                                           mother-                                                                            washing                                                                            of the                                                                            pect to the                                         product                                                                              solution                                                                           liquors                                                                            waters                                                                             residue                                                                           initial                                    Element  (%)    (g/l)                                                                              (g/l)                                                                              (g/l)                                                                              (%) product                                    __________________________________________________________________________    Zinc (Zn)                                                                              8.2    0    7.95 0.78 1.8 85.9                                       Lead (Pb)                                                                              4.5    0    0.12 0    6.3 2.5                                        Magnesium (mg)                                                                         2.5    0    3.2  0.32 0.08                                                                              98.4                                       Calcium (Ca)                                                                           5.1    0    5.1  0.55 0.22                                                                              97                                         Iron (Fe)                                                                              6.25   0    --   --   8   --                                         __________________________________________________________________________    Volume of mother-liquor recovered                                                                           1050 ml                                         Volume of washing waters recovered                                                                          500 ml                                          Weight of residual cake       79.8 g                                          __________________________________________________________________________

EXAMPLE X

    ______________________________________                                        Mixture to be treated                                                                             123 g of a mineral                                                            obtained from the slag                                                        heaps of a paper factory                                                      in France                                                 Aqueous phase for the suspension                                                                  1000 ml of a solution                                                         containing 180.8 g of                                                         magnesium chloride and                                                        1786.7 g of calcium                                                           chloride hexahydrate                                      Charge of chlorine  8.6 g per hour                                            Duration of the reaction                                                                          7 hours                                                   Working temperature 85° C.                                             ______________________________________                                        KINETICS OF THE ATTACK                                                             Composition                                                                   of the fully                                                                  dry starting                                                                             Composition of the solution after                             Ele- product    (g/l)                                                         ment (%)        1 h    2 h  3 h  4 h  5 h  6 h  7 h                           ______________________________________                                        Zinc 8.2        6.70   7.10 7.15 7.20 7.25 7.30 7.36                          (Zn)                                                                          Lead 4.5        5.1    5.2  5.0  4.7  4.3  4.4  4.2                           (Pb)                                                                          pH              3.2    2.8  2.8  2.8  3.3  3.1  3.1                           ______________________________________                                    

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                      Yield of                                            Composition                                                                          COMPOSITION        the attack                                          of the fully                                                                         of the                                                                             of the                                                                             of the   with res-                                           dry starting                                                                         starting                                                                           mother-                                                                            washing                                                                            of the                                                                            pect to the                                         product                                                                              solution                                                                           liquors                                                                            waters                                                                             residue                                                                           initial                                    Element  (%)    (g/l)                                                                              (g/l)                                                                              (g/l)                                                                              (%) product                                    __________________________________________________________________________    Zinc (Zn)                                                                              8.2    0    7.30 0.09 2.13                                                                              78.5                                       Lead (Pb)                                                                              4.5    0    4.35 0.23 1.25                                                                              78.8                                       Magnesium (Mg)                                                                         2.5                   0.49                                                                              84.8                                       Calcium (Ca)                                                                           5.1                   4.25                                                                              35.5                                       Iron (Fe)                                                                               6.25  0              6.65                                           __________________________________________________________________________    Volume of mother-liquor recovered                                                                           1010 ml                                         Volume of washing waters recovered                                                                          500 ml                                          Weight of residual cake       95.5 g                                          __________________________________________________________________________

EXAMPLE XI

Attack on the dusts from the smoke of the blast furnaces of Anzin

    __________________________________________________________________________    Mixture to be treated      100 g of dusts from the smoke                      Aqueous phase for the suspension                                                                         1000 ml of water                                   Charge of chlorine         8 g per hour                                       Duration of the reaction   51/2 hours                                         Working temperature        85° C.                                      __________________________________________________________________________    KINETICS OF THE ATTACK                                                                 Composition                                                                   of the fully                                                                  dry starting                                                                         Composition of the solution after                                      product                                                                              (g/l)                                                         Element  (%)    30 m                                                                              1 h 2 h  3 h 4 h 5 h 5.30 h                                                                            7 h                              __________________________________________________________________________    Zinc (Zn)                                                                              10.08  1   1.4 4    6.1 6.9 7.2 7.7                                  Lead (Pb)                                                                              6.88   --  --  --   --  --  0.37                                                                              0.45                                 Magnesium (Mg)                                                                         2.32   0.05                                                                              0.4 1    1.45                                                                              1.5 1.55                                                                              1.6                                  Calcium (Ca)                                                                           8.8    2.1 2.1 2.8  3.3 4.1 4.1 4.1                                  Iron (Fe)                                                                              27     <0.001                                                                            0.001                                                                             0.0015                                                                             0.002                                                                             0.009                                                                             0.076                                                                             0.056                                pH              6.9 6.85                                                                              4.8  2.9 2.5 2.4 2.4                                  Chloride (Cl.sup.-)                                                                           4   5.7 12.8 17.8                                                                              20.6                                                                              22.2                                                                              22.3                                 __________________________________________________________________________

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                  Yield of                                                 Composition                                                                          COMPOSITION   the attack                                               of the fully                                                                         of the                                                                             of the   with res-                                                dry starting                                                                         mother-                                                                            washing                                                                            of the                                                                            pect to the                                              product                                                                              liquors                                                                            waters                                                                             residue                                                                           initial                                        Element   (%)    (g/l)                                                                              (g/l)                                                                              (%) product                                        __________________________________________________________________________    Zinc (Zn) 10.08  5.38 0.34 5.57                                                                               50.7                                          Lead (Pb) 6.88   0.31 0.008                                                                              6.93                                                                              4.5                                            Magnesium (Mg)                                                                          2.32   1.67 0.09 0.76                                                                              70.2                                           Calcium (Ca)                                                                            8.8    5.65 0.81 2.80                                                                              69.3                                           Iron (Fe) 27     0.015                                                                              0.002                                                                              22.43                                              Cadmium (Cd)                                                                            0.05                                                                Manganese (Mn)                                                                          3.96                                                                Silver (Ag)                                                                             88 ppm                                                              Silica (SiO.sub.2)                                                                      3.68-3.76                                                           Aluminium (Al.sub.2 O.sub.3)                                                            0.91                                                                __________________________________________________________________________

EXAMPLE XII

    __________________________________________________________________________    Mixture to be treated     100 g of dust from blast                                                      furnaces                                            Aqueous phase for the suspension                                                                        1000 ml of a solution                                                         containing 180.8 g of                                                         magnesium chloride and                                                        1786.7 g of calcium chloride                                                  hexahydrate                                         Charge of chlorine        8 g per hour                                        Duration of the reaction  7 hours                                             Working temperature       85° C.                                       __________________________________________________________________________    KINETICS OF THE ATTACK                                                        Composition                                                                   of the                                                                        fully dry                                                                     starting     Composition of the solution after                                product      (g/l)                                                            Element                                                                             (%)    30 m                                                                              1 h 2 h 3 h 4 h 5 h 6 h 7 h                                  __________________________________________________________________________    Zinc (Zn)                                                                           10.08  2.6 3.6 4.25                                                                              5.3 5.75                                                                              5.9 7   5.3                                  Lead (Pb)                                                                           6.88   0.02                                                                              0.013                                                                             0.45                                                                              0.80                                                                              1   1.15                                                                              1.50                                                                              1.85                                 Iron (Fe)                                                                           27     0.0095                                                                            0.0095                                                                            0.0095                                                                            0.0095                                                                            0.0095                                                                            0.0095                                                                            0.0095                                                                            0.0095                               pH           5.8 5.2 4.1 3.8 3.7 3.6 3.4 3.3                                  __________________________________________________________________________

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                  Yield of                                                 Composition                                                                          COMPOSITION   the attack                                               of the fully                                                                         of the                                                                             of the   with res-                                                dry starting                                                                         mother-                                                                            washing                                                                            of the                                                                            pect to the                                              product                                                                              liquors                                                                            waters                                                                             residue                                                                           initial                                        Element   (%)    (g/l)                                                                              (g/l)                                                                              (%) product                                        __________________________________________________________________________    Zinc (Zn) 10.08  5.6  0.4  5.31                                                                              51.1                                           Lead (Pb) 6.88   1.9  0.082                                                                              5.50                                                                              25.2                                           Magnesium (Mg)                                                                          2.32             1.15                                                                              52.5                                           Calcium (Ca)                                                                            8.8              5.11                                                                              44.8                                           Iron (Fe) 27     0.01 0.004                                                                              20.38                                                                             0.06                                           Cadmium (Cd)                                                                            0.05                                                                Manganese (Mn)                                                                          3.96                                                                Silver (Ag)                                                                             88 ppm                                                              Silica (SiO.sub.2)                                                                      3.68-3.76                                                           Aluminium (Al.sub.2 O.sub.3)                                                            0.91                                                                __________________________________________________________________________    Volume of mother-liquors recovered                                                                        900 ml                                            Volume of washing waters recovered                                                                        600 ml                                            Weight of residual cake     95 g                                              __________________________________________________________________________

EXAMPLE XIII

The mixtures of oxides treated in Examples XIII to XVI were the residuesderived from a factory for the production of zinc situated in Crotone inItaly. The principal phases found in these residues are:

    ZnFe.sub.2 O.sub.4 --CaSO.sub.4, 2H.sub.2 O--ZnS--PbSO.sub.4 --ZnSO.sub.4, H.sub.2 O and CaSO.sub.4 1/2H.sub.2 O

    __________________________________________________________________________    Mixture to be treated     80 g of residue                                     Aqueous phase for the suspension                                                                        1000 ml of water                                    Charge of chlorine        8 g per hour                                        Duration of the reaction  6 hours                                             Working temperature       85° C.                                       __________________________________________________________________________    KINETICS OF THE ATTACK                                                                 Composition                                                                   of the                                                                        initial                                                                              Composition of the solution after                                      product                                                                              (g/l)                                                         Element  (%)    1 h 2 h 3 h 4 h 5 h 6 h                                       __________________________________________________________________________    Zinc (Zn)                                                                              13.5   3.5 3.7 3.7 4.2 4.3 4.6                                       Lead (Pb)                                                                              5.20   0.0058                                                                            0.00625                                                                           0.0074                                                                            0.008                                                                             0.0095                                                                            0.0106                                    Magnesium (Mg)                                                                         0.83   0.375                                                                             0.375                                                                             0.475                                                                             0.325                                                                             0.325                                                                             0.325                                     Calcium (Ca)                                                                           5.60   0.510                                                                             0.520                                                                             0.500                                                                             0.370                                                                             0.360                                                                             0.390                                     Iron (Fe)                                                                              15.6   0.083                                                                             0.104                                                                             0.115                                                                             0.225                                                                             0.275                                                                             0.350                                     pH              1.6 1.5 1.35                                                                              1.2 1.1 1.1                                       Chloride (Cl.sup.-)                                                                    --     3.7 5   5.6 7.3 7.9 8.7                                       __________________________________________________________________________

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                  Yield of                                                Composition                                                                          COMPOSITION    the attack                                              of the fully                                                                         of the                                                                             of the    with res-                                               dry starting                                                                         mother-                                                                            washing                                                                            of the                                                                             pect to the                                             product                                                                              liquors                                                                            waters                                                                             residue                                                                            initial                                        Element  (%)    (g/l)                                                                              (g/l)                                                                              (%)  product                                        __________________________________________________________________________    Zinc (Zn)                                                                              13.5   5    0.5  8.97 41.5                                           Lead (Pb)                                                                              5.20   0.0105                                                                             0.0025                                                                             5.55 0.24                                           Magnesium (Mg)                                                                         0.83   0.425                                                                              0.047                                                                              0.13 80.4                                           Calcium (Ca)                                                                           5.60   0.520                                                                              0.440                                                                              3.64 20.9                                           Iron (Fe)                                                                              15.6   0.4  0.030                                                                              13.61                                                                              3.6                                            __________________________________________________________________________    Volume of mother-liquors recovered                                                                        900 ml                                            Volume of washing waters recovered                                                                        560 ml                                            Weight of residual cake     95 g                                              __________________________________________________________________________

EXAMPLE XIV

    __________________________________________________________________________    Mixture to be treated     80 g of residue                                     Aqueous phase fot the suspension                                                                        1000 ml of water                                    Charge of chlorine        8 g per hour                                        Duration of the reaction  6 hours                                             Working temperature       85° C.                                       __________________________________________________________________________    KINETICS OF THE ATTACK                                                                 Composition                                                                   of the                                                                        initial                                                                              Composition of the solution after                                      product                                                                              (g/l)                                                         Element  product                                                                              1 h 2 h 3 h 4 h 5 h 6 h                                       __________________________________________________________________________    Zinc (Zn)                                                                              11.3   0.9 1.2 1.3 1.3 1.8 1.8                                       Lead (Pb)                                                                              7.25   0.0045                                                                            0.0048                                                                            0.0056                                                                            0.0058                                                                            0.006                                                                             0.00625                                   Magnesium (Mg)                                                                         0.47   0.030                                                                             0.0325                                                                            0.034                                                                             0.035                                                                             0.036                                                                             0.037                                     Calcium (Ca)                                                                           5.68   0.420                                                                             0.440                                                                             0.440                                                                             0.390                                                                             0.440                                                                             0.450                                     Iron (Fe)                                                                              19.1   0.140                                                                             0.144                                                                             0.146                                                                             0.147                                                                             0.151                                                                             0.151                                     pH              1.75                                                                              1.70                                                                              1.65                                                                              1.60                                                                              1.55                                                                              1.50                                      Chloride (Cl.sup.-)                                                                           2.3 2.5 2.8 3   3.2 3.4                                       __________________________________________________________________________

    __________________________________________________________________________    BALANCE SHEET OF THE ATTACK                                                                                  Yield of                                                Composition                                                                          COMPOSITION    the attack                                              of the fully                                                                         of the                                                                             of the    with res-                                               dry starting                                                                         mother-                                                                            washing                                                                            of the                                                                             pect to the                                             product                                                                              liquors                                                                            waters                                                                             residue                                                                            initial                                        Element  (%)    (g/l)                                                                              (g/l)                                                                              (%)  product                                        __________________________________________________________________________    Zinc (Zn)                                                                              11.3   1.7  0.16 9.52 18                                             Lead (Pb)                                                                              7.25   0.007                                                                              0.0025                                                                             6.95 0.2                                            Magnesium (Mg)                                                                         0.47   0.037                                                                              0.00004                                                                            0.41 8.6                                            Calcium (Ca)                                                                           5.68   0.590                                                                              0.360                                                                              21.1                                                Iron (Fe)                                                                              19.1   0.125                                                                              0.031                                                                              15.50                                                                              1.1                                            __________________________________________________________________________    Volume of mother-liquors recovered                                                                        890 ml                                            Volume of washing waters recovered                                                                        630 ml                                            Weight of residual cake     77 g                                              __________________________________________________________________________

The preceding description and examples allow those skilled in the art toappreciate the value and versatility of the process described above andto choose the correct operating conditions to solve their problems. Theywill moreover note the particular interest which there is in using thisprocess to separate the nickel from cobalt and the iron contained in thebasic carbonates of nickel and in the impure nickel oxides obtained fromthe roasting of mattes.

We claim:
 1. A process for the selective dissolution of oxygenatedcompounds containing at least a nickel compound selected from the groupconsisting of nickel oxide, nickel carbonate and mixtures thereof,present in a mixture of oxygenated compounds containing said nickelcompound and at least cobalt, copper and lead, comprising suspending themixture of the oxygenated compounds in an aqueous phase, treating theresulting aqueous suspension at a pH exceeding about 1 and at atemperature of from about 60° to 100° C. with chlorine to selectivelysolubilize said nickel compound while said cobalt, copper and leadremain in an essentially insoluble residue, and separating the aqueoussolution containing the dissolved said nickel compound from theinsoluble residue.